NA head on 951
03-18-2006, 06:45 PM
#1
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NA head on 951
Well i just found out that my head i was selling is not a 951 head that it is indeed a 944 NA head Any ideas why did this other then cost? performance? Looks like they did a 5 angle job on the intake side and 4 angle on the exhaust side? Thanks for ur input. 
03-18-2006, 08:23 PM
#6
Nordschleife Master
So is there any performance increase at all? I've read of 951 owners using 944 N/A cams..
Is there any compression difference with the way the n/a head is shaped?
Is there any compression difference with the way the n/a head is shaped?
03-19-2006, 12:46 AM
#7
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The Turbo and NA heads are identical except for the ceramic coating in the exhaust port. The exhaust valves are different – the turbo has sodium filled valve, NA doesn’t.
Chris White
Chris White
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03-19-2006, 08:01 AM
#8
There are several differencies compared 951 head & components to NA one.Chris mentioned ceramic coating.Here's several other differencies; cam 951 intake cam height is 12mm both 951 and NA.Exhaust cam height is 11mm on 951 and 12mm on NA cam.951 cam's specs are from early NA cam, factory changed design for 85½ and newer ones.There should be stamped 05R into 951 cam and 09R to NA one.Also the check valve is different in these heads.
951 intake valve's head has recess and circular journal NA intake valve head is with recess.951 exhaust valve head is comletely flat and NA exhaust valves head is with recess.951 exhaust valves are also sodium cooled.Also valve springs are different.Relaxed lenght of 951 spring is approx. 58mm compared to NA's 52mm.There are color codes; 951 ones have 3 redstripes on spring wire and NA ones have 3 white stripes.951 head have a stamped T-letter next to cast part number.
951 intake valve's head has recess and circular journal NA intake valve head is with recess.951 exhaust valve head is comletely flat and NA exhaust valves head is with recess.951 exhaust valves are also sodium cooled.Also valve springs are different.Relaxed lenght of 951 spring is approx. 58mm compared to NA's 52mm.There are color codes; 951 ones have 3 redstripes on spring wire and NA ones have 3 white stripes.951 head have a stamped T-letter next to cast part number.
03-19-2006, 03:52 PM
#9
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So, are there any advantages (or disadvantages) to using a NA head on a 951 motor? What about a (late) NA cam in a 951 motor? Will not having sodium filled exhaust valves be a problem (long-term or otherwise)? What about not having the ceramic coating?
